Balance SQLite expression tree for logical operators (AND/OR) to lower the depth (#2565)

* Modify toQueryString to chunk large list of ConditionParam

https://stackoverflow.com/a/17032196

* Add test for condition params chunking and wrapping in brackets

* Add support for chunkSize param in SearchDsl filters

* Update workflow engine dependency to use latest

* Refactor remove `chunkSize` parameter

* Recursively bifurcate expression tree to reduce depth

* Revert touched files not relevant for the PR

* Refactor toQueryString

* Update tests to include base cases for toQueryString

* Refactor and update related test cases

* Refactor test to make filter strict

---------

Co-authored-by: Jing Tang <[email protected]>

Author: LZRS

engine/src/androidTest/java/com/google/android/fhir/db/impl/DatabaseImplTest.kt

@@ -39,6 +39,7 @@ import com.google.android.fhir.search.Order
 import com.google.android.fhir.search.Search
 import com.google.android.fhir.search.StringFilterModifier
 import com.google.android.fhir.search.execute
+import com.google.android.fhir.search.filter.ReferenceParamFilterCriterion
 import com.google.android.fhir.search.getQuery
 import com.google.android.fhir.search.has
 import com.google.android.fhir.search.include
@@ -5178,6 +5179,32 @@ class DatabaseImplTest {
       assertThat(localChangeResourceReferences.size).isEqualTo(locallyCreatedPatients.size)
     }
 
+  @Test
+  fun searchTasksForManyPatientsReturnCorrectly() = runBlocking {
+    val patients = (0 until 990).map { Patient().apply { id = "task-patient-index-$it" } }
+    database.insert(*patients.toTypedArray())
+    val tasks =
+      patients.mapIndexed { index, patient ->
+        Task().apply {
+          id = "patient-$index-task"
+          `for` = Reference().apply { reference = "Patient/${patient.logicalId}" }
+        }
+      }
+    database.insert(*tasks.toTypedArray())
+
+    val patientsSearchIdList =
+      patients.take(980).map<Patient, ReferenceParamFilterCriterion.() -> Unit> {
+        { value = "Patient/${it.logicalId}" }
+      }
+    val searchQuery =
+      Search(ResourceType.Task)
+        .apply { filter(Task.SUBJECT, *patientsSearchIdList.toTypedArray()) }
+        .getQuery()
+
+    val searchResults = database.search<Task>(searchQuery)
+    assertThat(searchResults.size).isEqualTo(980)
+  }
+
   private companion object {
     const val mockEpochTimeStamp = 1628516301000
     const val TEST_PATIENT_1_ID = "test_patient_1"

engine/src/main/java/com/google/android/fhir/search/MoreSearch.kt

@@ -685,6 +685,8 @@ internal val DateTimeType.rangeEpochMillis
 
 data class ConditionParam<T>(val condition: String, val params: List<T>) {
   constructor(condition: String, vararg params: T) : this(condition, params.asList())
+
+  val queryString = if (params.size > 1) "($condition)" else condition
 }
 
 private enum class SortTableInfo(val tableName: String, val columnName: String) {

engine/src/main/java/com/google/android/fhir/search/filter/FilterCriterion.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021-2023 Google LLC
+ * Copyright 2021-2024 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -58,7 +58,7 @@ internal sealed class FilterCriteria(
     return SearchQuery(
       """
       SELECT resourceUuid FROM $entityTableName
-      WHERE resourceType = ? AND index_name = ? AND ${conditionParams.toQueryString(operation)} 
+      WHERE resourceType = ? AND index_name = ?${if (conditionParams.isNotEmpty()) " AND ${conditionParams.toQueryString(operation)}" else ""}
       """,
       listOf(type.name, param.paramName) + conditionParams.flatMap { it.params },
     )
@@ -85,16 +85,15 @@ internal sealed class FilterCriteria(
    * This function takes care of wrapping the conditions in brackets so that they are evaluated as
    * intended.
    */
-  private fun List<ConditionParam<*>>.toQueryString(operation: Operation) =
-    this.joinToString(
-      separator = " ${operation.logicalOperator} ",
-      prefix = if (size > 1) "(" else "",
-      postfix = if (size > 1) ")" else "",
-    ) {
-      if (it.params.size > 1) {
-        "(${it.condition})"
-      } else {
-        it.condition
-      }
+  private fun List<ConditionParam<*>>.toQueryString(operation: Operation): String {
+    if (this.size == 1) {
+      return first().queryString
     }
+
+    val mid = this.size / 2
+    val left = this.subList(0, mid).toQueryString(operation)
+    val right = this.subList(mid, this.size).toQueryString(operation)
+
+    return "($left ${operation.logicalOperator} $right)"
+  }
 }

engine/src/test/java/com/google/android/fhir/impl/FhirEngineImplTest.kt

@@ -17,6 +17,7 @@
 package com.google.android.fhir.impl
 
 import androidx.test.core.app.ApplicationProvider
+import ca.uhn.fhir.rest.gclient.TokenClientParam
 import ca.uhn.fhir.rest.param.ParamPrefixEnum
 import com.google.android.fhir.FhirServices.Companion.builder
 import com.google.android.fhir.LocalChange
@@ -26,6 +27,7 @@ import com.google.android.fhir.get
 import com.google.android.fhir.lastUpdated
 import com.google.android.fhir.logicalId
 import com.google.android.fhir.search.LOCAL_LAST_UPDATED_PARAM
+import com.google.android.fhir.search.filter.TokenParamFilterCriterion
 import com.google.android.fhir.search.search
 import com.google.android.fhir.sync.AcceptLocalConflictResolver
 import com.google.android.fhir.sync.AcceptRemoteConflictResolver
@@ -323,6 +325,36 @@ class FhirEngineImplTest {
       .isTrue()
   }
 
+  @Test
+  fun `search() should return patients filtered by param _id`() = runTest {
+    val patient1 = Patient().apply { id = "patient-1" }
+    val patient2 = Patient().apply { id = "patient-2" }
+    val patient3 = Patient().apply { id = "patient-45" }
+    val patient4 = Patient().apply { id = "patient-4355" }
+    val patient5 = Patient().apply { id = "patient-899" }
+    val patient6 = Patient().apply { id = "patient-883376" }
+    fhirEngine.create(patient1, patient2, patient3, patient4, patient5, patient6)
+
+    val filterValues =
+      listOf(patient2, patient3, patient1, patient5, patient4, patient6).map<
+        Patient,
+        TokenParamFilterCriterion.() -> Unit,
+      > {
+        { value = of(it.logicalId) }
+      }
+    val patientSearchResult =
+      fhirEngine.search<Patient> { filter(TokenClientParam("_id"), *filterValues.toTypedArray()) }
+    assertThat(patientSearchResult.map { it.resource.logicalId })
+      .containsExactly(
+        "patient-2",
+        "patient-45",
+        "patient-1",
+        "patient-4355",
+        "patient-899",
+        "patient-883376",
+      )
+  }
+
   @Test
   fun syncUpload_uploadLocalChange_success() = runTest {
     val localChanges = mutableListOf<LocalChange>()